MarkWest Energy Partners, L.P.

MarkWest Energy Partners, L.P. (NYSE: MWE) (“MarkWest” and “the Partnership”) announced today that its 2014 Annual Meeting of Common Unitholders will be held on Friday, June 6, 2014, at 9:00 a.m. Mountain Time at the Four Seasons Hotel Denver, located at 1111 14 th Street, Denver, Colorado 80202.

The record date for determination of unitholders entitled to vote at the meeting was April 11, 2014. Additional information, including details of the business to be conducted at the annual meeting, is included in MarkWest’s Notice of Annual Meeting and Proxy Statement, which was filed with the Securities and Exchange Commission. MarkWest’s 2014 Notice of Annual Meeting and Proxy Statement and 2013 Annual Report on Form 10-K may be accessed through the Partnership's website under “Investor Relations / Annual Reports & Proxy.”

In addition, MarkWest will host an Investor and Analyst Conference on Friday, June 6, 2014, at 9:15 a.m. Mountain Time at the Four Seasons Hotel Denver. To attend the conference, please RSVP before May 23, 2014, to investorrelations@markwest.com.

To listen to a live audio webcast and to view the related presentation materials for the Investor and Analyst Conference, please visit the “Presentations & Webcasts” link located under the Investor Relations section of the Partnership’s website at www.markwest.com. A replay of the presentation will also be available on the Partnership’s website.

MarkWest Energy Partners, L.P. is a master limited partnership engaged in the gathering, processing and transportation of natural gas; the gathering, transportation, fractionation, storage and marketing of natural gas liquids; and the gathering and transportation of crude oil. MarkWest has a leading presence in many unconventional gas plays including the Marcellus Shale, Utica Shale, Huron/Berea Shale, Haynesville Shale, Woodford Shale and Granite Wash formation.

This press release includes “forward-looking statements.” All statements other than statements of historical facts included or incorporated herein may constitute forward-looking statements. Actual results could vary significantly from those expressed or implied in such statements and are subject to a number of risks and uncertainties. Although MarkWest believes that the expectations reflected in the forward-looking statements are reasonable, MarkWest can give no assurance that such expectations will prove to be correct. The forward-looking statements involve risks and uncertainties that affect operations, financial performance, and other factors as discussed in filings with the Securities and Exchange Commission (SEC). Among the factors that could cause results to differ materially are those risks discussed in the periodic reports filed with the SEC, including MarkWest’s Annual Report on Form 10-K for the year ended December 31, 2013. You are urged to carefully review and consider the cautionary statements and other disclosures made in those filings, specifically those under the heading “Risk Factors.” MarkWest does not undertake any duty to update any forward-looking statement except as required by law.